Fix _MergedWrapperMarker to not include markers without corresponding execution scripts

[BruceForstall]

Don't include markers without execution scripts

[BruceForstall]

/azp run runtime-coreclr outerloop

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Issue Details

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Don't include markers without execution scripts

Author:	BruceForstall
Assignees:	BruceForstall
Labels:	area-Infrastructure-coreclr, needs-area-label
Milestone:	-

[BruceForstall]

This is a slight fix to #85441

[BruceForstall]

I verified that the only groups missing from a Pri-0 Linux-x64 test run now are:

HardwareIntrinsics_Arm_r
HardwareIntrinsics_Arm_ro

which is what we want, since they were the ones failing before.

[BruceForstall]

Failure in outerloop is #85081 (which is supposed to be disabled).

[ivdiazsa]

I've a question I left in a comment, but otherwise it LGTM! Thanks for fixing this Bruce

[BruceForstall]

fwiw, on a linux-x64 dev box you might build using:

	./build.sh -subset clr+libs -arch x64 -c checked
	./src/tests/build.sh checked x64

But on the CI, the build process is more like this (with many things happening on separate machines):

	./build.sh -subset clr.nativeprereqs -arch x64  -c checked
	./src/coreclr/build-runtime.sh checked x64 --keepnativesymbols
	./build.sh -subset tools+libs+libs.tests -configuration Debug -arch x64 -framework net8.0  -testscope innerloop /p:ArchiveTests=true
	./build.sh -subset clr.corelib+clr.nativecorelib+clr.nativeaotlibs+clr.tools+clr.packages+clr.paltestlist -arch x64 -c checked
	./src/tests/build.sh -log:Managed allTargets skipnative skipgeneratelayout skiptestwrappers checked x64 /p:TargetOS=AnyOS
	mkdir ~/gh/runtime/artifacts/tests/coreclr/linux.x64.Checked
	cp -r ~/gh/runtime/artifacts/tests/coreclr/AnyOS.x64.Checked/* ~/gh/runtime/artifacts/tests/coreclr/linux.x64.Checked
	./src/tests/build.sh skipmanaged skipgeneratelayout checked x64
	./src/tests/build.sh copynativeonly -log:Native checked x64 /p:LibrariesConfiguration=Debug
	./src/tests/build.sh buildtestwrappersonly -log:Wrappers checked x64 /p:LibrariesConfiguration=Debug
	./src/tests/build.sh generatelayoutonly -log:Layout checked x64 /p:LibrariesConfiguration=Debug

[trylek]

Thanks for landing the real fix Bruce!